The present invention relates to a sealing arrangement for sealing the gap between two concentric machine. elements which can move relative with respect to each other, the first machine element having a smooth contact surface and the second machine element having a profiled section which faces the contact surface of the first machine element and comprises a first flank, a second flank and a groove bottom which links the flanks, with a sealing ring which is axially fixed with respect to the second machine element by means of the profiled section and abuts sealingly at the contact surface of the first machine element, wherein the sealing ring is provided with a sealing edge and the sealing ring has a semi-circular cross-section.
Such a sealing element has become known from a publication in "India Rubber World", volume 125, No. 5, February 1952, pages 575 to 578, 581, New York, U.S.; T. J. McCuistion: "A new Rotary Seal for High-Speed and High-Pressure Applications".
O-rings of elastic materials are used as sealing elements per se or as spring elements for combination sealing arrangements. They can be exposed to axially and/or radially directed deformation forces. Although the O-ring is the smallest sealing element with respect to cross-section, the installing space is sometimes toleranced so closely that only O-rings of a small circumference can be implemented for sealing oscillating machine parts. The degree of deformation or pressing of the O-ring results in the sealing force. The reaction force due to the deformation and the pressure of the medium to be sealed sum up to the pressing force necessary for the seal. Yet if the circumference of the seal is small and the installing groove is manufactured inaccurately, the thus possibly resulting difficulties cannot be offset by a higher pressuring of the circumference's cross-section, because to do so a greater circumference would be needed. However, the installing conditions exclude the use of O-rings with a greater circumference.
The known sealing element is used as a rotary seal according to the teaching of the publication. The pressurized medium acts on the plane surface of the sealing element as shown. A pressure relief of the sealing element by the medium itself is not possible with this arrangement. There also exists the danger that the known sealing element moves with the rotating machine part. The known sealing element cannot be used to seal reciprocating machine parts.
Therefore it is the object of the present invention to develop a sealing element of the kind described above in such a way that it abuts on a surface to be sealed with a pressuring maximum and a small contact surface.
According to the present invention this object is solved in that the sealing edge has a conical surface open to the second flank or a first axially directed surface section and a second radially directed surface section relative to the sealing ring's axis, said second surface section facing the second flank.
Thus the sealing element according to the present invention has the considerable advantage that the sealing edge abuts at the surface to be sealed in a particularly friction-low manner. Thus an efficient sealing can be achieved to the detached machine part as well as to the groove bottom. The sealing element according to the present invention faces the high-pressure side either with a symmetrically designed peripheral surface or with a radially directed plane surface. Thus a deformation of the sealing ring under pressure can be effectively compensated. The sealing edge according to the present invention has the advantage that it can flow due to its plastic deformation when inserted without losing its originally intended shape. Thus an efficient sealing edge is kept still after the installation. If the sealing edge according to the present invention is pressurized and if reciprocating parts are sealed against each other, medium can be transferred from the low-pressure region to the high-pressure region due to the peripheral surface curved to the sealing edge. If the plane surface across from to the curved peripheral surface faces the high-pressure side, preferably reciprocating machine parts are sealed against each other. If this is the case, the plane surface of the sealing ring is separted from the flank and the sealing ring abuts with its curved peripheral surface at the opposing flank which faces the low-pressure side.
Moreover, the sealing arrangement according to the present invention has the advantage that it can be retrofit and can be fitted in the smallest profiles. Forms which are already available for the manufacture of O-rings can also be used for the production of the sealing element according to the present invention when equipped with minor changes. If the sealing ring according to the present invention has a semi-circular cross-section, half, viewed axially, of the originally needed fitting space can be saved. The large groove depth can be maintained. Thus a permanent pressure deformation can be compensated better. In pre-determined rectangular grooves, sealing rings according to the present invention can be inserted, which have a considerably larger diameter relative to the diameter of the rings with a round circumference when compared to the sealing rings with a round circumference as used previously. As a result, considerably greater sealing forces can be achieved thanks to the sealing ring according to the present invention compared to the known one. The sealing ring which is semi-circular in its cross-section can also be produced with the already existing forms for O-rings by using only one half of a production form and applying a plane smooth plate as counterpart to cover the correspondingly profiled half.
If the sealing ring according to the present invention is made of rubber elastic material, it can be used everywhere where the known O-rings are used for sealing machine parts. It is advantageous with the sealing ring according to the present invention that it needs less space compared to the known O-rings and that a sealing edge is also fashioned in the sealing ring according to the present invention compared to the common O-rings. If the sealing ring according to the present invention is made of tough elastic material it obtains its sealing force from the elastic deformation of a pre-stressing element with which the sealing ring made of tough elastic material cooperates. The pre-stressing element may be a rubber elastic stressing ring or stressing rings or a coil spring, hose spring or leaf spring. If the sealing ring is made of the tough elastic material polyurethane, the pre-stressing element may be left out.
For stabilizing the sealing ring according to the present invention a support ring of metal, ceramics or another material which is harder than the sealing ring may be used. By means of the support ring, the sealing ring is stabilized. Moreover, one or several support rings prevent a flowing or deformation of the sealing ring material under pressure. The support ring is stiff and hard when compared to the sealing ring made of elastic material and contributes to the form stability of the sealing ring. Therefore several support rings which respectively support sub-sections of the sealing ring can be preferable.
At its sealing edge, seen cross-sectionally, opposite to the curved peripheral surface, the sealing rings may also have a first and second surface section designed radially and axially to the sealing ring's axis and which discharge pressure from the sealing ring depending on the size of the design of these surface sections, when the pressurized medium abuts at these surface sections.
The sealing arrangement according to the invention thus lives up to all extended requirements which occur in the field of sealing technology. The sealing ring may be accommodated in axially tight and deep rectangular grooves, but it can also be fitted in other grooves, such as a trapezoidal or triangular groove. If the sealing ring according to the present invention is used instead of a O-ring, the material savings are considerable and the sealing ring according to the invention is also cheaper to be manufactured. Moreover, the surface of the sealing ring according to the present invention may be finished or a lubricant may be added to the material. The sealing ring may also be used as rotary seal in hydraulics or as hydraulic seal with axial movements.